GKT137831, a novel pyrazolopyridinedione derivative, a dual inhibitor of NADPH oxidases (NOX) 1 and NOX4, reduces inflammation in the ischemic retina by dampening the pro-inflammatory phenotype of retinal immune cells as well as macroglial Müller cells and neurons. In patients with diabetic kidney disease, GKT137831 demonstrated an excellent safety profile and statistically significant reduction in both liver enzyme and inflammatory marker levels in multiple phase I and phase II clinical studies. GKT137831 may be of significant benefit for patients with systemic sclerosis as studies in experimental models show that the compound may reduce the abnormal growth of connective tissue (fibrosis) and improve survival. GKT137831 was granted Orphan Drug designation for the treatment of systemic sclerosis from the FDA and the EMA. GKT-137831 acts as a Nox4 and Nox1 inhibitor ((Ki 100–150 nM). GKT-137831 attenuates hypoxia-induced pulmonary vascular cell proliferation. Also a potent inhibitor of fibrosis and hepatocyte apoptosis.